Hi, I have a 20x2 VFD labelled CU20026SCPB-t23a that I need help connecting. I have looked at the diagrams for the other t23a models that are avaible but they don't help me because my unit has a 26 pin connector and no separate power connector. The unit seems to have the same IC's as other noritake t23a's, with the SED2000 + the sed2032 as well as a motorola chip.

Does anyone here know how I can hook this up to my pc's parallel port?

Yes I have looked at the datasheets on the noritake website. Some models seem that they would be very similar but none of them have the 26 pin interface.

This unit is a replacement for the VFDs in the 'Millenium' payphone. The ribbon cable goes directly from the display to the pc board inside the phone... do you think that this VFD might be a custom-designed model that plugs directly into a 'parallel port' type interface on the mainboard?

I'm going to try emailing noritake for the pinout. Do you think that it might be the same for the first 16 pins as the other T23 models, and that the rest of the pins are for GND and +5V?

As they are microcontrollers there could be some custom program in it. Maybe if lucky it would be similar than in standard Noritake products and if the pinouts between the controllers are similar enough you could make a guess and try.

Anyway best way would be to get the datasheet for the display somewhere, which can be a bit difficult for custom products though.

Ok, I am trying to guess the pinout of the connector, and it isn't that easy

It looks to me like most of the data signals are on the odd-numbered pins (just the bottom row) and that the even numbers seem to be mostly for the power. As you can see in the picture, pins 22, 24, and 26 are all interconnected and appear to be the ground.

I have also marked off pins 2, 4, and 6 which seem to be where +5 v is connected since it looks like the are connected on the other side of the pcb. I checked by testing continuity from the pins to the leg of the large capacitor marked with a +.

The 9 pins in the black rectangle (1, 3, ..., 17) all lead directly to the M38802M2, so I think that they would be the 8 data pins and one other, enable perhaps?

The pins I have marked A, B, C, and D also lead to the same chip, but by different paths. Any idea what these might be?

Does this sound like it might be right? I really have no experience with displays like this. What connections do I still need to account for?

If looking at the CU20045SCPB-T23A datasheet the pins would be D0-D7, /WR, /CS, Sin (serial) and BUSY.

So that would make 4 pins beside the 8 datalines. But of course this display might have different interface and there could be /RD too or some other pins. But then the problem is trying to guess what goes where. Maybe if a datasheet for M38802M2 was available it could have pins with similar names.